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BAM Media M-197 LES Endo Agar (BD #273620)

February 2013

Bacteriological Analytical Manual

M197
LES Endo Agar (BD #273620)

(Formula source: Standard Method for Examination of Water and Wastewater, 1998, 20th ed., p. 9-58 (3)

Yeast extract1.2 g
Casitone or trypticase3.7 g
Thiopeptone or thiotone3.7 g
Tryptose7.5 g
Lactose9.4 g
Dipotassium hydrogen phosphate, K2HPO43.3 g
Potassium dihydrogen phosphate, KH2PO41.0 g
Sodium chloride, NaCl3.7 g
Sodium desoxycholate0.1 g
Sodium lauryl sulfate0.05 g
Sodium sulfite, Na2SO31.6 g
Basic fuchsin0.8 g
Agar15.0 g
Reagent grade water1 L

Rehydrate product in 1 L water containing 20 mL 95% ethanol. Do not use denatured ethanol, which reduces background growth and coliform colony size. Bring to a near boil to dissolve agar, then promptly remove from heat and cool to 45 to 50 °C. Do not sterilize by autoclaving. Final pH 7.2 ± 0.2. Dispense in 5- to 7- mL quantities into lower section of 60-mm sterile petri dishes. If dishes of any other size are used, adjust quantity to give an equivalent depth of 4-5 mm. Do not expose poured plates to direct sunlight; refrigerate in the dark, preferably in sealed plastic bags to reduce moisture loss. Discard unused medium after 2 weeks or sooner if there is evidence of moisture loss, medium contamination or medium deterioration (darkening of the medium).